Exam 3 Flashcards
Which of the following is a correct description of Ras?
G-protein that causes over expression of proteins when mutated
Which of the following are ways to create oncogenes from proto-oncogenes?
I) genes transported to new location with new promotor
When tumor suppressor genes suffer mutation the breaks are put on for transcription.
FALSE
What kind of enzyme is a tumor suppressor gene?
Activator
In order for a tumor to qualify as malignant…
) both oncogenes and tumor suppressor genes have to be present
Missense mutation in a proto-oncogene would be likely to create an oncogene.
TRUE
not all free living cells have genetic information that is double stranded.
FALSE
If a virus has a protein coat also mixed with phospholipids, it’s because of what?
It stole phospholipids from a cell
How does an influenza virus enter a cell?
It’s glycoprotein’s match the glycoprotein’s of the cell
Which of the following things does an influenza virus do to a cell that it hijacks?
I) It’s RNA acts as a template for transcription
Why is it so hard for scientists to fight the HIV virus?
newly created HIV DNA holds off at transcribing RNA
IV)it inserts DNA into the nucleus
A)I, III, IV
C)mutation of previously existing viruses
All of the above!
Prion’s are formed from eatin
BRAINS
In the polymerization of DNA, a phosphodiester bond is formed between a phosphate group of the nucleotide being added and _____ of the last nucleotide in the polymer.
3’ OH
DNA Complimentary Strands
Adenine to Thymine and Cytosene to Guanine
After DNA replication is completed, _____.
each new DNA double helix consists of one old DNA strand and one new DNA strand
The first step in the replication of DNA is catalyzed by _____.
Helicase
The action of helicase creates _____.
Replication forks and bubbles (think of ariel: the dinglehopper and the bubbles in the water!)
Why is the new DNA strand complementary to the 3’ to 5’ strands assembled in short segments?
DNA polymerase can assemble DNA only in the 5’ to 3’ direction
The synthesis of a new strand begins with the synthesis of a(n) _____.
RNA primer complementary to a preexisting DNA strand
An old DNA strand is used as a _____ for the assembly of a new DNA strand.
template
Short segments of newly synthesized DNA are joined into a continuous strand by _____.
ligase
Which of the following statements about DNA synthesis is true?
Primers are short sequences that allow the initiation of DNA synthesis.
Which part of a deoxynucleoside triphosphate (dNTP) molecule provides the energy for DNA synthesis?
Phosphate groups
Which of the following enzymes creates a primer for DNA polymerase?
Primase
Which of the following statements about Okazaki fragments in E. coli is true?
They are formed on the lagging strand of DNA.
Which of the following enzymes is important for relieving the tension in a helix as it unwinds during DNA synthesis?
Topoisomerase
What is meant by the description “antiparallel” regarding the strands that make up DNA?
The 5’ to 3’ direction of one strand runs counter to the 5’ to 3’ direction of the other strand.
Suppose you are provided with an actively dividing culture of E. coli bacteria to which radioactive thymine has been added. What would happen if a cell replicates once in the presence of this radioactive base?
DNA in both daughter cells would be radioactive.
In E. coli, there is a mutation in a gene called dnaB that alters the helicase that normally acts at the origin. Which of the following would you expect as a result of this mutation?
No replication fork will be formed
A new DNA strand elongates only in the 5’ to 3’ direction because _____.
DNA polymerase can add nucleotides only to the free 3’ end
Which of the following help(s) to hold the DNA strands apart while they are being replicated?
single-strand DNA binding proteins
Researchers found E. coli that had mutation rates one hundred times higher than normal. Which of the following is the most likely cause of these results?
The proofreading mechanism of DNA polymerase was not working properly.
Which of the following is most critical for the association between histones and DNA?
Histones are positively charged
A biochemist isolates, purifies, and combines in a test tube a variety of molecules needed for DNA replication. When she adds some DNA to the mixture, replication occurs, but each DNA molecule consists of a normal strand paired with numerous segments of DNA a few hundred nucleotides long. What has she probably left out of the mixture?
DNA ligase
The enzyme that synthesizes DNA is:
DNA Polymerase
During DNA synthesis, primase:
creates short segments of RNA that are complementary to the DNA template
remaining bases. What property of DNA makes these predictions possible?
complimentary base pairing
The enzyme that opens the two strands of DNA at the replication fork is:
Helicase
Primase is…
a RNA polymerase
DNA ligase is expected be most active on:
the lagging strand
. If histones were removed from a eukaryotic cell, what can reasonably be predicted?
DNA would not be coiled around nucleosomes
The redundant (degenerate) nature of the genetic code comes from the fact that:
There are more codons than amino acids
splicing is catalyzed by a …
ribozyme
If a cell lost one of its aminoacyl tRNA synthetases, which of the following would immediately be affected?
protein synthesis
amino acid held by a tRNA in the _______ site of the ribosome.
P;A
that person’s skin cells, you would find:
the exact same control elements present in nerve and skin cells
Enhancers are:
control elements in DNA
Alternative splicing allows for the:
existence of many more different polypeptides than genes
provides evidence for:
the conservation of master regulators of development
Which of the following is a mutation that could create an oncogene?
a mutation that leads to the overproduction of a proto-oncogene protein
The function of a tumor supressor gene is
. regulate cell division so that cells divide only when conditions are right
Gene families arise when:
a gene is duplicated and then each copy gradually accumulates different mutations
Which of the following statements about the human genome is true?
is used more often on the lagging strand
attached amino acid. This cell most likely has a defect in:
one of its aminoacyl tRNA synthetases
A gram-negative bacterium has:
an extra membrane outside the cell wall.
Which of the following statements about the Archaea is TRUE?
Based on molecular evidence, the Archaea are more closely related to the Eukaryotes than to the
case because
the ancestor to Euglena phagocytosed another photosynthetic eukaryotic organism.
Which of the following processes within viral replication is the greatest source of genetic variation in RNA virus populations?
High mutation rate due to lack of proofreading of RNA genome replication errors.
How do Prions effect other viruses
Unlike viruses, prions are infectious proteins.
Representation of gene density
Humans have ~20,000 protein-encoding genes in 2900 Mb.
What type of noncoding DNA comprises the largest portion of multicellular eukaryotic genomes?
transposers
How do retrotransposons differ from other transposons?
Retrotransposons move via an RNA transcript, whereas other transposons do not.
Because they both produce a reverse transcriptase, long interspersed nuclear elements (LINEs) as transposable elements may be related to _____.
retroviruses
Exon shuffling occurs during _____.
meiotic recombination
Which of the following is the correct sequence of these events in the origin of life?
synthesis of organic monomers, synthesis of organic polymers, formation of protobionts, formation of DNA-based genetic systems
Which free-living cells were the earliest contributors to the formation of Earth’s oxidizing atmosphere?
cyanobacteria
Penicillin is an antibiotic that inhibits enzymes from catalyzing the synthesis of peptidoglycan, so which prokaryotes should be most vulnerable to inhibition by penicillin?
gram positive bacteria
Which two structures play direct roles in permitting bacteria to adhere to each other, or to other surfaces?
capsules and fimbriae
Protists are alike in that all are
eukaryotic
- modification of protein
3,2,1,4
